[BUG] SofaRpcFallbackRegistryTest has order dependent tests

[SaaiVenkat]

Issue Description

Type: bug report

Describe what happened

• In com.alibaba.csp.sentinel.adapter.sofa.rpc.fallback.SofaRpcFallbackRegistryTest, the unit test testDefaultfallback() will fail when run after the unit test testCustomFallback().
• This is because the tests SofaRpcFallbackRegistryTest.testCustomFallback() pollutes the shared states SofaRpcFallback.providerFallback and SofaRpcFallback.consumerFallback between tests at
  

  Sentinel/sentinel-adapter/sentinel-sofa-rpc-adapter/src/test/java/com/alibaba/csp/sentinel/adapter/sofa/rpc/fallback/SofaRpcFallbackRegistryTest.java

  Line 49 in 5108046

  SofaRpcFallbackRegistry.setProviderFallback(new SofaRpcFallback() {

  
  

  Sentinel/sentinel-adapter/sentinel-sofa-rpc-adapter/src/test/java/com/alibaba/csp/sentinel/adapter/sofa/rpc/fallback/SofaRpcFallbackRegistryTest.java

  Line 62 in 5108046

  SofaRpcFallbackRegistry.setConsumerFallback(new SofaRpcFallback() {

• However, these states aren't cleaned after the test testCustomFallback() is run causing the above mentioned test to fail

Describe what you expected to happen

• The unit tests in com.alibaba.csp.sentinel.adapter.sofa.rpc.fallback.SofaRpcFallbackRegistryTest should pass when run in any order

How to reproduce it (as minimally and precisely as possible)

• In com.alibaba.csp.sentinel.adapter.sofa.rpc.fallback.SofaRpcFallbackRegistryTest, run the following unit tests in order
  • testCustomFallback()
  • testDefaultFallback()
• Running the tests in the above manner will produce java.lang.AssertionError

java.lang.AssertionError
	at org.junit.Assert.fail(Assert.java:86)
	at org.junit.Assert.assertTrue(Assert.java:41)
	at org.junit.Assert.assertTrue(Assert.java:52)
	at com.alibaba.csp.sentinel.adapter.sofa.rpc.fallback.SofaRpcFallbackRegistryTest.testDefaultfallback(SofaRpcFallbackRegistryTest.java:42)

Tell us your environment

• Sentinel: 1.8.6
• OS: Mac OS X 14.0 aarch64
• Java: 17.0.9 or 1.8.0_381

Anything else we need to know?

• I have raised a PR Fix order dependent tests in SofaRpcFallbackRegistryTest #3282 to fix this issue by resetting the polluter states SofaRpcFallback.providerFallback and SofaRpcFallback.consumerFallback to its default value after the test SofaRpcFallbackRegistryTest.testCustomFallback() is executed.